Lens barrel

ABSTRACT

A lens barrel of the present invention includes a fixed frame, a plurality of lens groups disposed on the inner circumference of the fixed frame movably along an optical axis direction with respect to the fixed frame, at least three lens holding frames for holding at least one lens group of a plurality of the lens groups, a cam frame having bottomed cam grooves to be coupled with the inner circumference of the fixed frame through cams, bottomed cam grooves across each other to be coupled with the lens holding frames through cams and a bottomed cam groove which is discontinued on one end surface and continued from the other end surface.

This is a division of application Ser. No. 08/359,415, filed Dec. 20,1994, now U.S. Pat. No. 5,818,647.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel, and more specifically toa lens barrel having a plurality of lens groups disposed therein so thatthey can extend and retract in an optical axis direction.

2. Related Art Statement

Conventionally, there are proposed various lens barrels for effectingzooming by moving frames for holding lens groups in an optical axisdirection by the rotation of a cam frame accommodated inside a fixedframe.

As an example of such lens barrels, Japanese Patent ApplicationLaid-open No. 53-102030 discloses a lens barrel provided with two fixedframes, wherein a first lens group is rotated and slid and a cam frameis driven by the rotation the thereof to drive the other lens groups.However, the lens barrel disclosed in the publication is disadvantageousin that its structure is complex and many parts are needed and furthersince th e the cam frame does not slide, an amount of movement of lensesis determined by the length of the cam frame.

Japanese Utility Model Publication No. 50-14511 discloses a lens barrelincluding a fixed frame, a cam frame which moves while being rotatedalong the cam of the fixed frame, and frames driven by the cam frame,wherein means for stopping the rotation of the frames is provided withthe fixed frame. In the lens barrel disclosed in the publication, sincethe fixed frame is provided with a linearly traveling groove and camsfor the cam frame, the disposition of the cams is regulated.

In the various kinds of proposed zoom lens barrels, when it is desiredto shorten the length of the lens barrel in a retracted state to makethe overall size of the lens barrel small, an amount of movement of lensgroups is increased and a longer cam frame is needed accordingly.

When the length of a zoom lens barrel is shortened in a retracted stateusing a short cam frame as in the lens barrel disclosed in JapanesePatent Application Laid-Open No. 3-180822, two mechanisms, i.e., amechanism for extending a lens frame unit to a certain position and amechanism for moving the lens barrel to a finally extended position fromthe above position are needed, thus the arrangement of the zoom lensbarrel is made complex.

When a cam frame which is long in an axis direction is used to retractlens groups whose amount of movement is increased, if the balancebetween the amount of movement of the lenses and the length of the camframe is lost, the cam frame may remain projected from a lens framealthough lenses are accommodated in the lens frame.

In particular, Japanese Patent Application Laid-Open No. 2-247624, forexample, discloses a zoom lens barrel as an example of the lens barrelsdescribed above which is arranged such that the lens holding frames forholding lens groups are each supported by rods.

As shown, for example, in FIG. 1, such a lens barrel sequentiallyaccommodates three lens holding frames 500b, 500c, 500d in this orderfrom the distal end to the proximal end of an optical axis on the innercircumference of a fixed frame 500a. A rod 500e is extended from thelens holding frame 500b of these lens holding frames which is disposedon the distal side of the optical axis to the proximal side of theoptical axis and inserted into bearings 500f and 500g, whereby the otherlens holding frames 500c, 500d are supported movably in the optical axisdirection.

In the lens barrel shown in FIG. 1, however, the rod 500e projects fromthe space of the lens barrel to the proximal side of the optical axis ina retracted state as shown in FIG. 2. Further, when the length of therod is shortened to prevent its projection in the retracted state, anamount of movement of the holding frames is reduced, by which the designof the lens barrel is greatly restricted, thus, for example, it isdifficult to design a zoom lens barrel having a high magnification.

In the lens barrels disclosed in Japanese Patent Application Laid-OpenNo. 3-39921, Japanese Patent Application Laid-Open No. 2-213813 and thelike, cam grooves are defined to the above cam frame, whereas camfollowers are defined to the above holding frames and the cam followersare engaged with the cam grooves of the cam frame to guide the holdingframes. With respect to the disposition of the cam grooves defined tothe cam frame, any one of the following arrangements is employed:bottomed cams are disposed only on any one of the inner circumferenceand the outer circumference of the cam frame; only passing-through camsare disposed; or a passing-through cam and a bottomed cam are disposedin combination. Further, bottomed cams are dislocated in an angulardirection or in an optical axis direction from an equally divided stateso that they do not cross each other.

When bottomed cams are disposed only on any of the inner circumferenceand the outer circumference of a cam frame as shown in the relatingtechnologies disclosed in Japanese Patent Application Laid-Open No.3-39921, Japanese Patent Application Laid-Open No. 2-213813 and thelike, the number of cams capable of being disposed on the cam frame andthe configuration of the cams are restricted, whereas when apassing-through cam and a bottomed cam are disposed in combination onthe cam frame, since these two kinds of cams cannot cross each other,their design is restricted. Therefore, the diameter of the cam framemust be increased or the length thereof in an optical axis directionmust be increased, by which the overall dimension of the cam frame isincreased. Further, when bottomed cams are disposed so that they do notcross each other, since they must be dislocated in an angular directionor in an optical axis direction from an equally divided state, theoverall dimension of the cam frame is also increased.

Further, in the lens barrel which is zoomed in such a manner that theholding frames for the lens groups are moved in an optical axisdirection by the rotation of the cam frame accommodated inside the fixedframe, a rotation stop member for the lens holding frames is needed tolimit the rotation of the lens holding frames which is caused by therotation of the cam frame. Japanese Patent Application Laid-Open No.2-201305 discloses an arrangement provided with a rotation stop memberas described above and a reinforcing member for reinforcing the strengthof a lens barrel, wherein a linear guide member is disposed as therotation stop member and a guide ring is disposed as the reinforcingmember and these separately provided members achieve the aboverespective functions. Further, a groove is defined to the frame memberwhose rotation is desired to be stopped and engaged with the abovelinear guide member to stop rotation.

When separate members are employed to stop the rotation of holdingmembers and to reinforce the strength of a lens barrel as in thearrangement disclosed in Japanese Patent Application Laid-Open No.2-201305, the number of parts is naturally increased and the arrangementof the frames is made complex. Further, when a groove is defined to aframe whose rotation is desired to be stopped and rotation is stopped bythe engagement of the groove with a rotation stop member, the length ofthe rotation stop member must be at least one half an amount of movementof the frame. Thus, when the rotation of a frame having a large amountof movement is to be stopped, a longer rotation stop member is neededaccordingly. As a result, the rotation stop member projects from thelens barrel in a retracted state, thus the length of the lens barrelcannot be shortened in the retracted state. Conversely, when the lengthof the lens barrel is shortened in the retracted state, the length ofthe rotation stop member is also shortened and the rotation of a framehaving a large amount of movement cannot be stopped.

Incidentally, there are conventionally proposed various kinds offlexible printed substrate structures having a U-shaped bent portion sothat they are accommodated in the aforesaid lens barrel.

For example, Japanese Patent Application Laid-Open No. 64-66995discloses an example of the flexible printed substrates arranged suchthat a plurality of flexible printed substrates each having a U-shapedbent portion and attached to relatively moving members are accommodatedin the state that the moving loci of the U-shaped bent portions are atleast partially overlapped each other to thereby reduce an accommodationspace.

In the structure disclosed in Japanese Patent Application Laid-Open No.64-66995, however, when the relatively moving members are going to move,since a force for straightly extending the flexible printed substrate isapplied thereto at the U-shaped portions, the force acts as a resistanceto the movement of the relatively moving members. When the flexibleprinted substrates overlap each other at the U-shaped bent portionswhere the resistance occurs, the resistance is increased and there is apossibility that the above members cannot be relatively moved.

OBJECT AND SUMMARY OF THE INVENTION

A first object of the present invention is to provide a small lensbarrel.

A second object of the present invention is to provide a lens barrelwhose length is shortened when it is retracted.

A third object of the present invention is to provide a lens barrelwhich can achieve a large amount of displacement in an optical axisdirection by the smaller number of frame members.

A fourth object of the present invention is to provide a lens barrelwhich can achieve a large amount of displacement in an optical axisdirection by the smaller number of frame members and whose length isshortened when it is retracted.

A fifth object of the present invention is to provide a lens barrel witha sufficient strength which includes lens holding frames having a largeamount of movement and whose length is shortened when retracted.

A sixth object of the present invention is to provide a small lensbarrel having a cam frame in which a cam groove is effectively disposedin a small space.

A seventh object of the present invention is to provide a lens barrelhaving a flexible printed substrate structure enabling relatively movingmembers to smoothly move by reducing a resistance produced at the bentportion of the flexible printed substrate.

When simply described, a lens barrel of the present invention includes afixed frame, a plurality of lens groups disposed in the innercircumference of the fixed frame and movable along an optical axisdirection with respect to the fixed frame, a lens holding frame forholding at least one of the lens groups, a cam frame coupled with theinner circumference of the fixed frame through a cam and moving alongthe optical axis direction with respect to the fixed frame by beingrotated about an optical axis with respect to the fixed frame.

These as well as other objects and advantages of the present inventionwill become further apparent from the following detailed explanation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross sectional view along an optical axisshowing a state that a conventional lens barrel is extended;

FIG. 2 is a longitudinal cross sectional view along an optical axisshowing a state that a conventional lens barrel is retracted;

FIG. 3 is a longitudinal cross sectional view along an optical axisschematically showing a state that a lens barrel of an embodiment of thepresent invention is extended;

FIG. 4 is a longitudinal cross sectional view along an optical axisshowing a state that the lens barrel of FIG. 3 is retracted;

FIG. 5 is a perspective view showing an arrangement for mounting thelens barrel of the above embodiment on a camera body;

FIG. 6 is a longitudinal cross sectional view showing a camera of theabove embodiment;

FIG. 7 is an exploded perspective view showing a zoom lens barrel ofanother embodiment extended in an optical axis direction;

FIG. 8 is an exploded perspective view showing a second group frame,third group frame, fourth group frame and fifth group frame of the aboveembodiment extended in an optical axis direction;

FIG. 9 is a front view showing a lens unit mounted on a lens plate ofthe above embodiment;

FIG. 10 is a perspective view showing a key mounted on the lens plate ofthe above embodiment;

FIG. 11 is a perspective view showing a lens plate of FIG. 10 from theopposite side thereof;

FIG. 12 is an exploded perspective view showing a first zoom frame,screw frame, and first group frame of the above embodiment extended inan optical axis direction;

FIG. 13 is an enlarged perspective view showing a lens drive unit of theabove embodiment in detail;

FIG. 14 is a cross sectional view schematically showing the upper halfportion of an optical axis of the lens barrel of the above embodiment;

FIG. 15 is a cross sectional view showing the upper half portion on anoptical axis of the lens barrel of the above embodiment when it iszoomed;

FIG. 16 is a front view, partly in cross section, of the lens barrel ofthe above embodiment when viewed from a front side;

FIG. 17 is an enlarged perspective view showing the U-shaped bentportion of a flexible printed substrate of the above embodiment;

FIG. 18 is a developed view showing a cam provided with a cam frame ofthe above embodiment;

FIG. 19 is a developed view showing a cam provided with a fixed frame ofthe above embodiment;

FIG. 20 is a longitudinal cross sectional view along an optical axisshowing the lens barrel of the above embodiment when it is retracted;

FIG. 21 is a longitudinal cross sectional view along an optical axisshowing the lens barrel of the above embodiment located at a wide end;

FIG. 22 is a longitudinal cross sectional view along an optical axisshowing the lens barrel of the above embodiment in a standard state;

FIG. 23 is a longitudinal cross sectional view along an optical axisshowing the lens barrel of the above embodiment located at a telephotoend;

FIG. 24 is a flowchart showing operation when the lens barrel of theabove embodiment is zoomed from a retracted state to a wide position;

FIG. 25 is a flowchart showing operation when the lens barrel of theabove embodiment is zoomed from a wide side to a telephoto side;

FIG. 26 is a flowchart showing operation when the lens barrel of theabove embodiment is zoomed from the telephoto side to an arbitraryzoomed position; and

FIG. 27 is a flowchart showing operation when the lens barrel of theabove embodiment is retracted.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

First, the concept of a lens barrel in an embodiment of the presentinvention will be described with reference to examples shown in FIG. 3and FIG. 4.

The lens barrel accommodates, for example, three lens holding frames400b, 400c, 400d which are sequentially disposed in this order from thedistal side to the proximal side of an optical axis on the insidediameter side of a fixed frame 400a. Of these lens holding frames, a rodmember 400e is extended from the lens holding frame 400b disposed on thedistal side of the optical axis to the proximal side thereof as well asa rod member 400h is extended from the lens holding frame 400d disposedon the proximal side of the optical axis to the distal side thereof andthe lens holding frame 400c can be moved in an optical axis direction bybeing supported in such an arrangement that the rod members 400e, 400hare inserted into a bearing 400f.

Note, the above rod members 400e, 400h are disposed at the positionssubstantially equally divided in a circumferential direction (i.e. theylie on a common diameter).

As shown in FIG. 4, this arrangement enables the length of the lensbarrel to be shortened when the lens holding frames have a large amountof movement and the lens barrel is retracted in the state that the rodmembers provided with the lens holding frames do not project from thespace of the lens barrel even if it is retracted.

FIG. 5 is a perspective view showing an arrangement for mounting thelens barrel of the embodiment on a camera body and FIG. 6 is alongitudinal cross sectional view showing a camera.

The camera of the embodiment includes as its main components the camerabody 74, a front panel 74 fixed on the front surface of the camera body74 by screws 76 threaded from rear side of the camera body and having amirror 75a and a finder 75b, a lens plate 46 fixed to the camera body 74at a position in front of the front plate 75 by screws 72 threadedlythrough the lens plate 46, the lens plate 46 having a lens unit 73disposed on the front surface thereof and reinforcing the strength ofthe entire lens barrel, a rear cover 77 engaged with the camera body 74from the rear side thereof so that is abutted against the camera body 74through a projection 77a, and a front cover 78 engaged with the lensplate 46 from the front side thereof so that it is abutted against thelens plate 46b through a projection 78a.

FIG. 7 is an exploded perspective view showing a zoom lens barrel ofanother embodiment extended in an optical axis direction and FIG. 8 isan exploded perspective view showing the main portion of lens holdingframes.

The zoom lens barrel includes a first group frame 38 for holding a firstgroup lens, a second group frame 1 for holding a second group lens, athird group frame 5 for holding a third group lens, a fourth group frame13 for holding a fourth group lens and a fifth group frame 19 forholding a fifth group lens which are sequentially disposed in this orderfrom the distal side (object side) of an optical axis along the axis.

A cam frame 24 is disposed on the outer circumferential side of thesecond group frame 1, the third group frame 5, the fourth group frame 13and the fifth group frame 19, a first zoom frame 31 which is threadedlyengaged with the first group frame 38 through a screw portion 39 isdisposed around the cam frame 24 and further a fixed frame 34 isdisposed around the first zoom frame 31 and fixedly mounted on the lensplate 46.

The second group frame 1 includes a circumferential-wall-shapedprojected portion 1c projecting from the end face of the frame 1 on theproximal side of the optical axis (the camera body side) in the opticalaxis direction within a predetermined circumferential area. Theprojected portion 1c has a rotation stop key way 1b defined on the outercircumference thereof and a key way 1d defined on the innercircumference thereof each in parallel with the optical axis and a rod 2extending in the optical axis direction. The second group frame 1 hasthree pins 3 which project from it integrally therewith to the outsideand are located at the positions shown and are equally divided in thecircumferential direction of the frame 1. Three projections 30 areformed with respect to the pins 3 at the positions substantially equallydivided in a circumferential direction on the distal side of the opticalaxis (the object side). The second group frame 1 further has a key way1a parallel with the optical axis (refer to FIG. 9).

The third group frame 5 has substantially cylindrical bearings 7, 8, 9disposed at the positions substantially equally divided in acircumferential direction, respectively, each of the bearings havingsleeves 6 at both ends thereof. The bearing 8 of these bearings has aprojection 23 projecting on the proximal side in the axis direction (onthe camera body side) and the projection 23 has a pin 12 projectingoutwardly and integrally formed therewith. Further, the third groupframe 5 has a guide projection 10 disposed at a position between thebearing 7 and the bearing 8 in a circumferential direction and extendingto the proximal side in the optical axis direction and a guideprojection 11 disposed at a position between the bearing 8 and thebearing 9 and extending to the proximal side in the optical axisdirection.

The fourth group frame 13 has a pin 15 projecting from the circumferencethereof outwardly and formed integrally therewith and a rotationstopping groove 16 defined to the circumference thereof. Further, a rod14 directed to the distal side of the optical axis in parallel therewithis attached to the fourth group frame 13 and the groove 16 and the rod14 are disposed at the positions substantially equally divided in acircumferential direction. In addition, the fourth group frame 13 has astepping motor 17 for adjusting a diaphragm and a band-shaped substrate18 is extended from the stepping motor 17.

The fifth group frame 19 has a pin 22 integrally formed therewith andextending outwardly and a rotation stop groove 20 defined thereto.Further, a rod 21 directed to the distal side of the optical axis inparallel therewith is attached to the outer circumference of the fifthgroup frame 19 and the groove 20 and the rod 21 are disposed at thepositions substantially equally divided in a circumferential direction.

Note, when these rods 2, 14 and 21 are made to have the same diameter,respectively, the bearings corresponding to them can be also made tohave the same diameter, by which a manufacturing cost can be reduced.

Th cam frame 24 is a cylindrical member having several bottomed cams 26which constitute a cam mechanism and are defined on the innercircumference thereof and an internal gear 29 is partially formed on theinner circumference of the cam frame 24 at the end on the proximal sideof the optical axis (on a photographer side) thereof. Further, severalbottomed cams 25 constituting a cam mechanism are also defined on theouter circumference of the cam frame 24 as well as an encoder 28 whichis mounted thereon and three pins 27 integrally project from the end onthe proximal side of the optical axis of the cam frame 24.

The first zoom frame 31 has three linear traveling grooves 33 defined onthe inner circumference thereof at the positions equally divided in acircumferential direction, respectively. Further, pins 50, 51, 52integrally project from the inner circumference of the first zoom frame31 as well as a substantially rectangular projection 49 extends from theproximal end on the inner circumference of the frame 31 and a pin 32separate from the first zoom frame 31 is disposed upon the projection49.

The fixed frame 34 is a cylindrical member having cams 112 on the innercircumference thereof and a ring 36 is engaged with the fixed frame 34at the end thereof on the distal side in the optical axis direction anda substrate 35 having a photoreflector (PR) 48 is attached on the outercircumference of the fixed frame 34. Further, several bosses 37 arespaced about and project from the proximate end circumferential surfacein the optical axis direction of the fixed frame 34 along acircumferential direction.

The lens plate 46 is composed of a sheet-shaped member having holes 47defined at the four corners thereof and has a key 40 serving as areinforcing member and a key 42 serving as a similar reinforcing memberattached thereto in such a manner that they are vertical with respect tothe front surface of the lens plate 46. A multiplicity of thin lightshield grooves 41 are defined in the key 40 perpendicular to the opticalaxis and a pinion gear 43 extending in the optical axis direction ismounted on the key 42. Further, a zoom motor 45 as a drive source and asecond gear box 44 having a gear train for transmitting a drive forcefrom the zoom motor 45 are mounted on the lens plate 46. The final gearof the gear train is meshed with the pinion gear 43 mounted on the key42.

Next, the alignment of the respective lens holding frames will bedescribed below.

The third group frame 5 is movable in the optical axis direction withrespect to the second group frame 1 by the arrangement that the rod 2 isinserted into the bearing 8 and further the position in the radialdirection of the third group frame 5 is determined with respect to thesecond group frame 1 by the bearings 7, 9 which regulate the radialdirection.

The fourth group frame 13 is movable in the axis direction with respectto the third group frame 5 by the arrangement that the rod 14 isinserted into the bearing 7 and further the position in the radialdirection of the fourth group frame 13 is determined with respect to thethird group frame 5 by the groove 16 engaged with the guide projection11.

The fifth group frame 19 is movable in the axis direction with respectto the third group frame 5 by the arrangement that the rod 21 isinserted into the bearing 9 and further the position in the radialdirection of the fifth group frame 19 is determined with respect to thethird group frame 5 by the groove 20 engaged with the guide projection10.

More specifically, the respective lens holding frames are aligned witheach other in such a manner that the fourth group frame 13 and the fifthgroup 19 are positioned with respect to the third group frame 5 and thethird group frame 5 is positioned with respect to the second group frame1.

Further, the other frame members are aligned as described below.

The position in the radial direction of the cam frame 24 is determinedin such a manner that the pins 3, 12, 15, 22 are engaged with the cam 26on the inner circumference of the can frame 24.

Further, the position in the radial direction of the cam frame 24 isdetermined in such a manner that the pin 50 of the first zoom frame 31is engaged with the cam 25 and the position in the radial direction ofthe second group frame 1 is determined in such a manner that theprojections 30 at the three positions are engaged with the linearlytraveling grooves 33 at the three positions of the first zoom frame 31,respectively with respect to the first zoom frame 31. The position ofthe first group frame 38 is determined in such a manner that the screwportion 39 is threadedly engaged with the extreme end of the first zoomframe 31.

The position in the radial direction of the cam frame 24 is determinedwith respect to the fixed frame 34 in such a manner that the three pins27 are engaged with the cams 112 at the three positions of the fixedframe 34.

The position of the fixed frame 34 is determined by fitting the bosses37 to the lens plate 46 and the rotation of the second group frame 1about the optical axis is regulated by fitting the key 40 to the key way1b of the second group frame 1.

Since the respective lens holding frames are supported as describedabove, the length of the lens barrel in its retracted state issubstantially made equal to the sum of the lengths in the axialdirection of the second group frame 1, the third group frame 5, thefourth group frame 13 and the fifth group frame 19, so that the lengthin the optical axis of the lens barrel can be remarkably shortened.

FIG. 9 is a front view of the lens unit 73 mounted on the lens plate 46and FIG. 10 is a perspective view showing the keys 40, 42 mounted on thelens plate 46.

As described above, the keys 40, 42 extending to the distal side of theoptical axis in parallel therewith are fixed on the front surface of thlens plate 46 through key mounting units 40a, 42a provided with the keys40, 42.

A light shield groove is also defined on the inside of the key 42similar to the key 40 and an arm 94 circumferentially extends from thekey 42. The arm 94 has a pinion gear 43 with a long shaft disposedthereon, the pinion gear 43 is held between the arm 94 and the lensplate 46 and the lower portion of the pinion gear 43 has a differentgear diameter.

Since there is a possibility that the pinion gear 43 may bend because itis a long shaft, it is made of metal to avoid the bending.

The key 40 and the key 42 are fitted to the key ways 1b, 1a defined onthe second group frame 1, respectively to regulate the rotation of thesecond group frame 1. Further, since these keys 40, 42 are made ofmetal, they can also reinforce the lens unit 73.

The key 40 and the key 42 can be formed from, for example, an aluminiumdiecast product, zinc diecast or the like and the respective componentsof the frame members including the second group frame 1 and the like maybe molded by a plastic material or the like which is lighter and lessrigid, by which the key 40 and the key 42 substantially assure therigidity of the entire lens unit 73 and serve as a reference when therespective components of the lens barrel are positioned.

Note, the rotation of the first zoom frame 31 about the optical axis isregulated in such a manner that the three linear traveling grooves 33which are disposed on the inner circumference of the first zoom frame 31and parallel with the optical axis direction are engaged with the threeprojections 30 disposed on the outer circumference of the second groupframe 1 on the distal side of the optical axis.

Next, the arrangement of a zoom gear mounted on the lens plate 46 willbe described with reference to FIG. 11.

The above key 40 for regulating the rotation of the second group frame 1about the optical axis and the long shaft pinion gear 43 for rotatingthe cam frame 24 are mounted on the front surface (the lower surface inFIG. 11) of the lens plate 46 on which the lens barrel is fixed.Further, the zoom motor 45, a first gear box 241 containing three-stagedplanetary gear mechanisms and the second gear box 44 containing thetrain of external gears, are mounted on the rear surface (the uppersurface in FIG. 11) of the lens plate 46.

The zoom motor 45 constitutes the first stage planetary gear mechanismin the first gear box 241 using a pinion gear mounted on the outputshaft thereof as a sun gear.

A carrier on the final stage in the first gear box 241 is meshed withthe eternal gear in the second gear box 44 and transmits a drive forcethrough a gear 235 meshed with a gear 236 which has a disk 237integrally disposed on the rear surface thereof and is rotatedtherewith, the disk having a plurality of slits defined therethrough inits circumference direction.

The gear 235 is integrally and coaxially provided with a gear 243 havinga different diameter on the front surface thereof. In addition, there isprovided an idle gear 244 which is meshed with the gear 243 and furthermeshed with a gear 242 mounted on the base end portion of the piniongear 43 and having a different diameter.

Further, a C-shaped photointerrupter (PI) 239 is disposed and holds thedisk 237 therebetween and a flexible substrate 238 is attached to thephotointerrupter 239.

When the zoom motor 45 rotates, the planetary gear mechanisms in thefirst gear box 241 are driven and successively the gear train in thesecond gear box 44 is driven. Further, the gear 236 and the disk 237 arerotated through the gear 235.

When the slits of the disk 237 pass through the photointerrupter 239,light passes through the slits and signals flow to the flexiblesubstrate 238. On the other hand, when the portion of the disk 237without the slits passes therethrough light is interrupted and no signalflows to the flexible substrate 238. Therefore, when the disk 237rotates, a pulse wave flows to the flexible substrate 238.

On the other hand, when the gear 243 is rotated by the rotation of thegear 235, the gear 242 is rotated through the gear 244 and the longshaft pinion gear 43 is driven in rotation accordingly.

As shown in FIG. 7, since the pinion gear 43 is meshed with the internalgear 29 of the cam frame 24 and the pins 27 of the cam frame 24 aremeshed with the cams 112 of the fixed frame 34 at the three positions,when the pinion gear 43 rotates, the cam frame 24 is moved forwardlyalong the cams 112 while rotating about the optical axis.

The rotation about the optical axis of the second group frame 1, thethird group frame 5, the fourth group frame 13 and the fifth group frame19 is regulated by the key 42, they move forward and backward along thecam 26 on the inner circumference of the cam frame 26 in on the axialdirection without being rotated.

The photoreflector 48 of the substrate 35 attached to the fixed frame 34is provided with a light emitting element and a light receiving elementand light emitted from the light emitting element is reflected on theouter circumference of the cam frame 24 and incident on the lightreceiving element. Since the encoder 28 mounted on the cam frame 24 hasa light reflectance ratio which is larger than that of the other portionof the circumference of the cam frame 24, when the encoder 28 passesthrough a position corresponding to the photoreflector 48, signalsoutput from the photoreflector 48 are changed.

When the cam frame 24 rotates, W+1(a few pulses after the wide (WIDE)end) is supposed to be a time at which an end 28a of the encoder 28passes through the photoreflector 48, T−1 (a few pulses before thetelephone (TELE) end) is supposed to be time at which the other end 28bof the encoder 28 passes through the photoreflector 48 and thephotointerrupter 239 is reset at these times.

When the lens barrel is zoomed from its retracted position to the wideend or the telephoto end or from a standard (STD) end to the wide end orthe telephone end, the lens barrel is caused to surely pass through thereset position of the photointerrupter 239 and the dispersion of thepulses of the photointerrupter 239 resulting from backlash iseliminated. As a result, zooming can be carried out so that the camframe 24 stops at an accurate position.

FIG. 12 is an exploded perspective view showing lens drive unit 157provided with the first zoom frame 31, a screw frame 142 and the firstgroup frame 38 by extending them in an optical axis direction.

As shown in FIG. 12, the first group frame 38 having the screw portion39 formed on the outer circumference thereof is disposed forwardly ofthe screw frame 142 and the first zoom frame 31 having the lens driveunit (LD unit) 157 located on the inner circumference thereof isdisposed rearwardly of the screw frame 142.

The screw frame 142 has a screw portion 143 defined at the extreme endon the inner circumference thereof, an internal gear 144 defined in apredetermined range at the rear end of the inner circumference along itscircumferential direction and a helicoid 145 defined at the rear end ofthe outer circumference thereof along its circumferential direction.Further, the screw frame 142 has two projections 146, 147 in thevicinity of the terminal end of the internal gear 144. One of theprojections 147 projects in the inside diameter direction of the screwframe 142 and the other projection 146 projects toward the proximal sideof the optical axis.

On the other hand, the lens drive unit 157 mounted on the innercircumference of the first zoom frame 31 includes a motor 153 as a drivesource, a gear box 149 containing a gear train for reducing a driveforce from the motor 153 and a gear 152 to which an output from the gearbox 149 is transmitted, and an LD flexible substrate (lens driveflexible substrate) 155 is attached to the motor 153. Further, the lensdrive unit 157 has a projection 156 projecting toward the front side ofthe first zoom frame 31 along the axis thereof.

Further, the first zoom frame 31 has a helicoid 151 defined on the frontside of the inner circumference thereof along its circumferentialdirection and a projection 150 projecting in an inside diameterdirection is formed at an edge portion of the helicoid 151 and furtheran arm 154 is disposed on the inside of the first zoom frame 31 to guidethe LD flexible substrate 155.

The first group frame 38 is mounted on the screw frame 142 through thescrew portion 39 thereof threadedly engaged with the screw portion 143of the screw frame 142 and the screw frame 142 is mounted on the firstzoom frame 31 through the helicoid 145 thereof threadedly engaged withthe helicoid 151 of the first zoom frame 31.

When a focusing operation is carried out in the arrangement shown inFIG. 12, the motor 153 is driven to rotate the gear 152 through the geartrain in the gear box 149. Since the gear 152 is meshed with theinternal gear 144 in the screw frame 142, the screw frame 142 is rotatedby the rotation of the gear 152 and moved along the helicoid 151 in theoptical axis direction as well as the first group frame 38 is alsoextracted, so that the focusing operation is carried out.

When focusing is effected to an object very near to the camera, thescrew frame 142 rotates in the direction of an arrow B so that theprojection 147 is butted against the projection 156 of the first zoomframe 31 and acts as a stopper.

Further when focusing is effect to an object at an indefinite distance,the screw frame 142 rotates in the direction of an arrow A so that theprojection 146 is abutted against the projection 150 to act as astopper.

FIG. 13 shows the lens drive unit 157 in detail.

The lens drive unit 157 includes the motor 153 as the drive source, apinion gear 175 mounted on the output shaft of the motor 153, two gears181, 174 meshed with the pinion gear 175, the gear box 149 employingtwo-staged planetary gear mechanisms for transmitting a drive force fromthe gear box 149, the gear 152 to which an output from the gear box 149is transmitted to rotate the screw frame 142, a disk 176 having aplurality of slits 176b circumferentially arranged and disposed on thelower surface of the gear 181 in the figure and a C-shapedphotointerrupter 177 disposed to hold the disk 176 vertically.

An end of the LD flexible substrate 155 is divided into two ends and oneof them 155b is attached to the photointerrupter 177 and the other end155a is attached to the motor 153. The LD flexible substrate 155 isattached to the arm 154 circumferentially extending from the lens driveunit 57 and supported thereby.

When the lens drive unit 157 is driven, power is fed to the motor 153through the LD flexible substrate 155 first and when the motor 153rotates, the gears 181, 174 are rotated by the pinion gear 175.

The drive force of the gear 174 is transmitted to the gear 152 throughthe gear box 149. Since the gear 152 is meshed with the internal gear144 disposed on the screw frame 142, the screw frame 142 is rotated tocarry out focusing as described above.

Further, when the gear 181 rotates, the disk 176 is also rotated. Sinceone of the two projections 177a, 177b of the C-shaped photointerrupter177 is provided with a light emitting element and the other is providedwith a light receiving element, when the slits 176b pass between theprojection 177a and the projection 177b of the photointerrupter 177,light emitted by the light emitting element is received by the lightreceiving element and an electric power generated by thephoto-to-electro conversion executed by the light receiving elements istransmitted to the end 155b of the LD flexible substrate 155. On theother hand, when the portion 176a of the disk 176 without the slitspasses between the projection 177a and the projection 177b of thephotointerrupter 177, since light emitted from the light emittingelement is interrupted and no electric power is generated in the lightreceiving element, no electric power is transmitted to the end 155b ofthe LD flexible substrate 155.

Therefore, a pulse wave flows to the end 155b of the LD flexiblesubstrate 155 by the rotation of the disk 176. The number of the pulsesis counted by a not shown counter and counting is executed by countingan instant at which an electric current flows to the motor 153 from anearest state as a zero pulse.

Further, focusing is controlled to stop the screw frame 142 at aposition to be focused without error in such a manner that a voltageimposed on the motor 153 is reduced a few pulses before the position sothat a brake is applied after the rotational speed of the motor 153 isreduced.

As shown in FIG. 14, the lens barrel of the aforesaid embodimentincludes the fixed frame 34 which does not move at the times whenzooming is effected and the like, the first zoom frame 31 disposed onthe inner circumference of the fixed frame 34 and having the lens driveunit 157 mounted thereon, the cam frame 24 disposed on the further innercircumference of the first zoom frame 31, the screw frame 142 disposedon the inner circumference of the first zoom frame 31 on the front sidethereof, the first group frame 38 mounted through the screw frame 142,the fourth group frame 13 with a not shown diaphragm disposed inwardlyof the cam frame 24 behind the first group frame 38, the lens plate 46,which is composed of the substantially rectangular sheet member and hasthe fixing holes at the four corners thereof, disposed behind the fixedframe 34 to fix the same perpendicularly to the optical axis (also referto FIG. 16) and the key 40 disposed between the cam frame 24 on thefront side of the lens plate 46 and the fourth group frame 13 toregulate the rotation of the lens barrel.

Further, the lens barrel includes a flexible printed substrate fordiaphragm 18 having an end connected to the diaphragm of the fourthgroup frame 13 and the lens driving flexible printed substrate 155 forexecuting focusing having an end connected to the lens drive unit 157.

These two flexible printed substrates 18, 155 enter the lens barrel fromthe outside thereof through a gap between the lens plate 46 and thefixed frame 34, travel along the lens plate 46 toward the optical axisat the center of the lens barrel in an overlapped state, are bentforwardly on the outer circumference side of the key 40, extendforwardly along the guide groove 40b defined to the key 40 (refer toFIG. 16) and are bent into a U-shape rearwardly in the vicinity of thefront side of the extreme end of the key 40.

The flexible printed substrate 155 is guided by the arm 154 (refer toFIG. 16) substantially circumferentially extended from the lens driveunit 157.

The flexible printed substrate for diaphragm 18 is bent rearwardly afterpassing through the U-shaped bent portion and then connected to thestepping motor 17 (refer to FIG. 7) disposed on the front side thefourth group frame 13 and a not shown photointerrupter.

On the other hand, after the lens drive flexible printed substrate 155passes through the U-shaped bent portion, it is connected to the motor153 provided with the lens drive unit 157 and the photointerrupter 177while supported by the arm 154 substantially circumferentially extendingfrom the lens drive unit 157.

When the lens barrel as described above is zoomed, the cam frame 24 isextended with respect to the fixed frame 34 and the first zoom frame 31is extended with respect to the fixed frame 34 and also with respect tothe cam frame 24, as shown in FIG. 15. Thus, the fourth group frame 13is relatively extended with respect to the respective frames 34, 24 and31 as shown in the figure.

When the zooming operation is effected as described above, the U-shapedbent portions of the flexible printed substrate for diaphragm 18 and thelens drive flexible printed substrate 155 are moved forwardly anddisposed as shown in FIG. 15.

In the retracted state and at the telephoto end, these two flexibleprinted substrates 18, 155 are disposed so that they do not overlap eachother at the U-shaped bent portions thereof as shown in FIG. 16 and FIG.17 in more detail.

More specifically, the flexible printed substrate for diaphragm 18 andthe lens drive flexible printed substrate 155 have narrow width portions190a, 191a, respectively which are arranged such that one of them isdisposed by being biased on the right side and the other is disposed bybeing biased on the left side at the U-shaped bent portion so that theydo not overlap each other in a thickness direction.

With this arrangement, even if the first zoom frame 31 and the fourthgroup frame 13 move, a resistance applied the U-shaped bent portions canbe reduced.

Further, a fine gap is formed between the narrow width portion 190a atthe U-shaped bent portion of the lens drive flexible printed substrate155 and the narrow width portion 191a at the U-shaped bent portion ofthe flexible printed substrate for diaphragm 18 so that no friction isgenerated by the contact between flexible printed substrates.

Further, a lubrication processing may be applied to the portion wherethe lens drive flexible printed substrate 155 is in contact with theflexible printed substrate for diaphragm 18 by coating lubricatinggrease or the like to a portion thereof to lower a friction resistancetherebetween.

FIG. 18 is a developed view showing the cam disposed on the came frame24 and FIG. 19 is a developed view showing the cam disposed on the fixedframe 34. FIG. 20 is a longitudinal cross sectional view along anoptical axis showing the lens barrel in a retracted state, FIG. 21 is alongitudinal cross sectional view along an optical axis showing the lensbarrel at the wide end. FIG. 22 is a longitudinal cross sectional viewalong an optical axis showing the lens barrel in the standard state, andFIG. 23 is a longitudinal cross sectional view along an optical axisshowing the lens barrel at the telephoto end.

As shown in FIG. 18, the bottomed cam 26 disposed on the innercircumference of the cylinder cam frame 24 is composed of six bottomedcams 100, 101, 102, 103, 104 and 105 to be described in more detail,whereas the bottomed cam 25 disposed on the outer circumference thereofis composed of four bottomed cams 106, 107, 108 and 109 to be describedin more detail.

The cams 101, 103 and 105 of the cams on the inner circumference havethe same cam configuration and are disposed at positions substantiallyequally divided in a circumferential direction, respectively.

The cam 102 crosses the cam 101 at a cam follower introducing portion310.

The cams 106, 107 and 108 disposed on the outer circumference have thesame cam configuration and cam 107 is divided at a portion shown bynumeral 300 midway thereof and disposed as the cam 109 from a portionshown by numeral 301.

Further, holes are drilled at the positions where the cams disposed onthe inner circumference cross the cams disposed on the outercircumference. For example, a hole—not shown—is drilled at the positionwhere the cam 103 on the inner circumference is across the cam 106 onthe outer circumference.

The depth of the cam groove of each of the bottomed cams disposed on thecam frame 24 is set such that the sum of the depth of the cam groove onthe inner circumference and the depth of the cam groove on the outercircumference is smaller than the wall thickness of the cam frame 24.

The three pins 3 projecting from the circumference of the second groupframe 1 are engaged with the three cams 101, 103 and 105, the pin 22disposed on the fifth group frame 19 is engaged with the cam 100, thepin 15 disposed on the fourth group frame 13 is engaged with the cam 102and the pin 12 disposed on the third group frame 5 is engaged with thecam 104.

Further, the three pins 50, 51 and 52 integrally disposed on the firstzoom frame 31 are engaged with the three cams 106, 108 and 109 on theouter circumference, respectively and the pin 32 disposed on the firstzoom frame 31 as a separate member is engaged with the cam 107.

Although the cams 106, 108 are engaged with the pins 50 and 51 in theoverall stroke thereof, respectively, the pins 32 is removed from thecam 107 at the portion shown by numeral 300. Substantially at the sametime, the pin 52 is engaged with the cam 109 so that the three cams areengaged with the three pins at all times in the cam frame 24 and thefirst zoom frame 31.

On the other hand, the three cams 112 each having the same camconfiguration are disposed on the inner circumference of the fixed frame34 at the positions substantially equally divided in a circumferentialdirection. The three pins 27 projecting from the outer circumference ofthe cam frame 24 are engaged with these three cams 112, respectively.

When the lens barrel is in the retracted state, the three pins 3provided with the second group frame 1 are engaged at the positions ofcam ends 101a, 103a and 105a, respectively, the pin 12 provided with thethird group frame 5 is engaged at the position of a cam end 104a, thepin 15 is provided with the fourth group frame 13 is engaged at theposition of a cam end 102a and the pin 22 provided with the fifth groupframe 19 is engaged at the position of a cam end 100a.

Further, the three pins 50, 51 and 52 provided on the first zoom frame31 are engaged at the positions of cam ends 106a, 108a and 109a. The pin27 disposed on the outer circumference of the cam frame 24 is engaged atthe position of a cam end 112a.

At that time, the first group frame 38, the second group frame 1, thethird group frame 5, the fourth group frame 13 and the fifth group frame19 have a positional relationship shown in FIG. 20, respectively.

When the cam frame 24 rotates, it moves along the cams 112 of the fixedframe 34, the second group frame 1 moves along the cams 101, 103 and 105of the cam frame 24, the third group frame 5 moves along the cam 104 ofthe cam frame 24, the fourth group frame 13 moves along the cam 102 ofthe cam frame 24, and the fifth group frame 19 moves along the cam 100of the cam frame 24.

Although the pin 3 disposed on the second group frame 1 is unstable atthe position of the cam follower introducing portion 310 where the cam101 crosses the cam 103, since the other two pins 3 are engaged with thecams 103, 105, respectively, the cam follower introduction portion 310can be passed through without serious affect to operation.

When the pins provided with the respective frames pass through a holesuch as that denoted by numeral 110 where the cam on the innercircumference of the cam frame 24 is across the cam on the outercircumference thereof, the pin securely moves on the cam because the sumof the depth of the cam groove on the inner circumference side and thedepth of the cam groove on the outer circumference side is set smallerthan the wall thickness of the cam frame 24 as described above so thatthe pins are not simultaneously engaged at the hole.

When the lens barrel is located at the zoomed wide end, the three pins 3of the second group frame 1 are engaged at the positions of inflectionpoints 101b, 103b and 105b, respectively, the pin 12 of the third groupframe 5 is engaged at the position of an inflection point 104b, the pin15 of the fourth group frame 13 is engaged at the position of aninflection point 102b, and the pin 22 of the fifth group frame 19 isengaged at the position of an inflection point 100b.

Further, the pins 50, 51 of the first zoom frame 31 are engaged at thepositions of inflection points 106b and 108b, respectively and the pin32 of the first zoom frame 31 is engaged at the position of aninflection point 107b. In addition, the pin 27 of the cam frame 24 isengaged at the position of an inflection point 112b.

At that time, the first group frame 38, the second group frame 1, thethird group frame 5, the fourth group frame 13 and the fifth group frame19 have a positional relationship shown in FIG. 21, respectively.

When the lens barrel is located at the zoomed telephoto end, the threepins 3 of the second group frame 1 are engaged at the positions of camends 101c, 103c and 105c, the pin 12 of the third group frame 5 isengaged at the position of a cam end 104c, the pin 15 of the fourthgroup frame 13 is engaged at the position of a cam end 102c and the pin22 of the fifth group frame 19 is engaged at the position of a cam end100c.

Further, the pins 50 and 51 of the first zoom frame 31 are engaged atthe positions of cam ends 106c and 108c, respectively and the pin 32 ofthe first zoom frame 31 is engaged at the position of a cam end 107c. Inaddition, the pin 27 of the cam frame 24 is engaged at the position of acam end 112c.

At that time, the first group frame 38, the second group frame 1, thethird group frame 5, the fourth group frame 13 and the fifth group frame19 has a positional relationship shown in FIG. 23, respectively.

When the lens barrel is in the standard state, the three pins 3 of thesecond group frame 1 are engaged between the inflection point 101b andthe cam end 101c, between the inflection point 103b and the cam end 103cand between the inflection point 105b and the cam end 105c,respectively, the pin 12 of the third group frame 5 is engaged betweenthe inflection point 104b and the cam end 104c, the pin 15 of the fourthgroup frame 13 is engaged between inflection point 102b and the cam end102c, and the pin 22 of the fifth group frame 19 is engaged between theinflection point 100b and the cam end 100c.

Further, the pins 50 and 51 of the first zoom frame 31 are engagedbetween the inflection point 106b and the cam end 106c and between theinflection point 108b and the cam end 108c, respectively and the pin 32of the first zoom frame 31 is engaged between the inflection point 107band the cam end 107c. In addition, the pin 27 of the cam frame 24 isengaged between the inflection point 112b and the cam end 112c.

At that time, the first group frame 38, the second group frame 1, thethird group frame 5, the fourth group frame 13 and the fifth group frame19 have a positional relationship shown in FIG. 22, respectively.

Next, a flow diagram for zooming the lens barrel from the retractedstate to a wide side will be described with reference to FIG. 24.

When a not shown power switch provided with the camera is turned on, avoltage is applied to the zoom motor 45 to drive it clockwise (step S1).At that time, the lens barrel is displaced in the wide direction and asignal is outputted from the photointerrupter (abbreviated as PI in FIG.24), 239, a not shown timer is reset (step S2), and the monitor of thephotointerrupter 239 and an output from the photoreflector (abbreviatedas PR in FIG. 24) 48 is started.

When an output from the photoreflector 48 is switched to high (H) (stepS3), braking is applied to the zoom motor 45 (step S4) and it isconfirmed by the output from the photointerrupter 239 that the zoommotor 45 is stopped. At that time, the content of the output counter ofthe photointerrupter 239 is rewritten to the predetermined “number ofpulses (W+1) at the switched position of the photoreflector 48” (stepS5).

Next, a voltage is applied to the zoom motor 45 to drive iscounterclockwise (step S6) and when the falling down (i.e., fallingedge) of the photointerrupter 239 is sensed (step S7), the content ofthe counter of the photointerrupter 239 is decremented by 1 (step S8).

Then, when it is sensed that the content of the counter of thephotointerrupter 239 becomes W+α which indicates the position just infront of the wide position by an amount corresponding to the given pulse(α) (Step S9), a voltage for driving the zoom motor 45 is reduced (stepS10) and when it is confirmed that content of the counter of thephotointerrupter 239 becomes the predetermined value W after the speedof the lens barrel is reduced (step S11), braking is applied to the zoommotor 45 (step S12) to stop the lens barrel at a target wide position.

Further, when an output from the photoreflector 48 is low (L) at stepS3, the rising (rising edge) up of the photointerrupter 239 is sensed(step S13), and when it is sensed, the timer is reset (step S14) and theprocess returns to step S3. Further, when a predetermined time elapseswithout sensing the rising up of the photointerrupter 239 (step S15), itis determined to be extraordinary.

Further, when a predetermined time elapses without sensing the fallingdown of the photointerrupter 239 at step S7 (step S16), it alsodetermined to be extraordinary.

Next, a flow for zooming the lens barrel from the wide side to thetelephoto side will be described with reference to FIG. 25.

When the not shown power switch provided with the camera is turned on, avoltage is applied to the zoom motor 45 to drive it clockwise (step S21)and the lens barrel starts to be displaced in the telephoto direction.At that time, a signal is output from the photointerrupter 239, thetimer is reset (step S22), and the monitor of the photointerrupter 239and an output from the photoreflector 48 is started.

Although an output from the photoreflector 48 is switched to high (H) inthe midway of the process, at that time the content of the outputcounter of the photointerrupter 239 is rewritten to the predetermined“number of pulses (W+1) at the switched position of the photoreflector48”.

An output from the photoreflector 48 is switched to low (L) in thevicinity of the telephoto side (step S23). At that time the content ofthe output counter of the photointerrupter 239 is rewritten to thepredetermined “number of pulses (T−1) at the switched position of thephotoreflector 48” (step S24). When it is sensed that the content of thecounter of the photointerrupter 239 becomes T−α which indicates theposition just in front of the telephoto position by an amountcorresponding to the given pulse (α) (step S25), a voltage for drivingthe zoom motor 45 is reduced (step S26) and when it is confirmed thatcontent of the counter of the photointerrupter 239 becomes T after thespeed of the lens barrel is reduced (step S27), braking is applied tothe zoom motor 45 (step S28) to stop the lens barrel at a targettelephoto position.

Further, when an output from the photoreflector 48 is high (H) at stepS23, the rising up of the photointerrupter 239 is sensed (step S29), andwhen it is sensed, the timer is reset (step S30) and the process returnsto step S23. Further, when a predetermined time elapses without sensingthe rising up of the photointerrupter 239 (Step S31), it is determinedto be extraordinary.

Next, a flow for zooming the lens barrel from the telephoto side to anarbitrary zoom position will be described with reference to FIG. 26.

When a zoom switch is turned on, a voltage is applied to the zoom motor45 to drive it counterclockwise (step S41) and the lens barrel starts tobe displaced in the wide direction. At that time, a signal is outputfrom the photointerrupter 239, the timer is reset (step S42), and themonitor of the photointerrupter 239 and an output from thephotoreflector 48 is started.

When it is sensed in the midway of the process that an output from thephotoreflector 48 is switched to high (H) (step S43), the content of theoutput counter of the photointerrupter 239 is rewritten to thepredetermined “number of pulses (T−1) at the switched position of thephotoreflector 47” (step S44). Thereafter, when the zoom switch isturned off in the midway of the process (step S45), braking is appliedto the zoom motor (step S46) to stop the lens barrel.

When the zoom switch is not turned off in the midway of the zoomingprocess (step S45), an output from the photoreflector 48 is switched tolow (L) at a position just in front of the wide position. At that timethe content of the output counter of the photointerrupter 239 isrewritten to the predetermined “number of pulses (W+1) at the switchedposition of the photoreflector 48” (step S50).

When it is sensed that the content of the counter of thephotointerrupter 239 becomes W+α which indicates the position just infront of the wide position by an amount corresponding to the given pulse(α) (step S51), a voltage for driving the zoom motor 45 is reduced (stepS52) and when the content of the counter of the photointerrupter 239becomes W after the speed of the lens barrel is reduced (step S53),brake is applied to the zoom motor 45 (step S54) to stop the lens barrelat a target wide position.

Further, when an output from the photoreflector 48 is low (L) at stepS43, the rising up of the photointerrupter 239 is sensed (step S47), andwhen it is sensed, the timer is reset (step S48) and the process returnsto step S43. Further, when a predetermined time elapses without sensingthe rising up of the photointerrupter 239 (step S49), it is determinedto be extraordinary.

Next, a flow when the lens barrel is retracted will be described withreference to FIG. 27.

When the power switch is turned on, a voltage is applied to the zoommotor 45 to drive it counterclockwise (step S61) and the lens barrelstarts to be displaced in a retracting direction. At that time a signalis output from the photointerrupter 239, the timer is reset (step S62),and the monitor of the photointerrupter 239 and an output from thephotoreflector 48 is started.

When an output from the photoreflector 48 is low (L) (step S63), thecontent of the output counter of the photointerrupter 239 is rewrittento the predetermined “number of pulses (W+1) at the switched position ofthe photoreflector 48” (step S64).

When it is sensed that the content of the counter of thephotointerrupter 239 becomes α which indicates the position just infront of the retracted position by an amount corresponding to the givenpulse (α) (step S65), a drive voltage applied to the zoom motor 45 isreduced (step S66) and when it is sensed that the content of the counterof the photointerrupter 239 becomes 0 after the speed of the lens barrelis reduced (step S67), braking is applied to the zoom motor 45 (stepS68) to stop the lens barrel at a target retracted position.

Further, when an output from the photoreflector 48 is high (H) at stepS63, the rising up of the photointerrupter 239 is sensed (step S69), andwhen it is sensed, the timer is reset (step S70) and the process returnsto step S63. Further, when a predetermined time elapses without sensingthe rising up of the photointerrupter 239 (step S71), it is determinedto be extraordinary.

As described above, according to the embodiment, since there areprovided the fixed frame having the internal cam, the cam frame formoving the lens barrel group holding frames in the optical axisdirection while being rotated by the internal cam on the innercircumference side thereof, the long shaft pinion gear for driving theinternal gear of the cam frame and the key member for regulating therotation of the lens group holding frames, a lens barrel having a largeamount of movement in the optical axis direction can be realized by thesmaller number of frames and thus when the lenses are retracted, thelength of the lens barrel can be shortened.

With respect to the disposition of the cams of the cam frame, since thebottomed cams are disposed on both sides of the frame, i.e. on the innercircumference and the outer circumference and the cams are disposed insuch a manner that the cams on the inner circumference are across thecams on the outer circumference at at least one position and one of thecams is divided at at least one position, the cams can be effectivelydisposed in a small space and the size of the cam frame can be reducedin the optical axis direction. As a result, the size of the zoom lensbarrel can be reduced.

With respect to the method of supporting the lens holding frames forholding the lens groups, since the zoom lens barrel provides thebearings with the lens holding frame serving as the reference forsupporting the rods, the rods are provided with the other lens holdingframes and the rods are disposed at the positions substantially equallydivided in a circumferential direction, the rods can be effectivelysupported in a small space. As a result, the length of the zoom lensbarrel can be shortened in the retracted state.

With respect to the flexible printed substrates each having at least oneU-shaped bent portion, since a plurality of the flexible printedsubstrates are arranged such that they do not overlap each other at theU-shaped bent portions, a resistance which is applied to the relativelymoving members such as the lens holding frames and the like by theU-shaped bent portions can be reduced and as a result the above memberscan be smoothly moved.

Further, since the rotation of the frames for holding the lens groups isstopped and the strength of the lens barrel is reinforced by the keycomposed of the same member, the arrangement of the lens barrel can besimplified. In addition, as a method of stopping rotation, since thelens holding frame whose rotation is stopped by the key regulates therotation of the other lens holding frames, the rotation of the frameshaving a large amount of movement can be stopped using a short key,whereby the length of the lens barrel can be shortened in the retractedstate.

In this invention, it is apparent that working modes different in a widerange can be formed on this basis of this invention without departingfrom the spirit and scope of the invention. This invention is notrestricted by any specific embodiment except as may be limited by theappended claims.

What is claimed is:
 1. A lens barrel, comprising: a fixed first frame; aplurality of lens groups disposed on an inner circumference of saidfixed first frame and movable along an optical axis direction withrespect to said fixed first frame; lens holding frames for holding atleast one of said lens groups; and a cam frame for moving said lensholding frames in an optical axis direction responsive to rotation aboutan optical axis with respect to said fixed first frame, said cam framehaving a plurality of bottomed cam grooves engaged by cam followersprovided on said lens holding frames, at least two of a plurality ofsaid bottomed cam grooves cross each other at at least one position ofan inner circumference or other circumference of said cam frame.
 2. Alens barrel according to claim 1, wherein said two bottomed cam grooveswhich cross each other are formed on the inner circumference and theouter circumference of said cam frame, respectively at least one of thebottomed cams being a non-linear cam.
 3. A lens barrel according toclaim 1, wherein said two bottomed cam grooves which cross each otherare formed on the inner circumference of said cam frame.
 4. A lensbarrel according to claim 1, wherein said two bottomed cam grooves whichcross each other are formed on the outer circumference of said camframe.
 5. A lens barrel according to claim 1, wherein positions where aplurality of said bottomed cam grooves cross each other are positionswhere said cam followers are located when said lens barrel is not used.6. A lens barrel, comprising: a fixed first frame; a plurality of lensgroups disposed on an inner circumference of said fixed first frame andmovable along an optical axis direction with respect to said fixed firstframe; lens holding frames for holding at least one of said lens groups;a cam frame coupled with the inner circumference of said fixed firstframe through cams and moving along the optical axis direction withrespect to said fixed first frame responsive to rotation about saidoptical axis with respect to said fixed first frame; a plurality ofbottomed cam grooves provided with said cam frame with which camfollowers provided with said lens holding frames are engaged and atleast one of a plurality of said bottomed cam grooves is a non-linearcam groove and is divided at at least one position of a front endsurface or rear end surface of said cam frame.
 7. A lens barrel,comprising: a fixed first frame; a plurality of lens holding framesmovable along an optical axis direction with respect to said fixed firstframe; a cam frame for moving a plurality of lens groups along theoptical axis direction with respect to said fixed first frame responsiveto rotation about said optical axis with respect to said fixed firstframe; and a plurality of bottomed cam grooves provided with said camframe with which cam followers provided with said lens holding framesare engaged and at least one of a plurality of said bottomed cam groovesis a non-linear cam groove and is divided at at least one position of afront end surface or rear end surface of said cam frame.
 8. A lensbarrel comprising: a cam frame with cam grooves respectively provided onan inner periphery and an outer periphery thereof; and at least firstand second frame members each having cam followers which engage withsaid cam grooves respectively provided within the inner periphery andabout the outer periphery of said cam frame; wherein a depth of a camgroove provided the inner periphery of said cam frame and a depth of acam groove provided on the outer periphery of said cam frame is set tobe smaller than a thickness of said cam frame measured in a radialdirection, at least one of said cam grooves being non-linear.